Could a simple blood test predict risk of suicide?

Being able to identify those at high risk for suicide is vital for prevention, but there is not currently a reliable way to predict this risk. Now, researchers from Johns Hopkins University School of Medicine in Baltimore, MD, say they have found a chemical alteration in a gene linked to stress responses that could enable the creation of a blood test to predict a person's risk of suicide consistently.

The study's findings could help in creating a test to identify those at risk of committing suicide.

The study, led by Zachary Kaminsky, assistant professor of psychiatry and behavioral sciences at Johns Hopkins, is published in The American Journal of Psychiatry.

According to the Centers for Disease Control and Prevention (CDC), in 2009, suicide was the 10th leading cause of death in the US among persons aged 10 and older, resulting in 36,891 deaths overall.

"Suicide is a major preventable public health problem," says Kaminsky, "but we have been stymied in our prevention efforts because we have no consistent way to predict those who are at increased risk of killing themselves."

He adds that their test could help them "stem suicide rates by identifying those people and intervening early enough to head off a catastrophe."

Their findings suggest that alterations in a gene that plays a role in the brain's response to stress hormones is involved in turning ordinary reactions to everyday stresses into suicidal tendencies.

To conduct their study, Kaminsky and his team aimed their attention at a genetic mutation in a gene called SKA2. They analyzed brain samples from deceased people, some of whom had been mentally ill and some of whom had been healthy. They found that the samples of people who died by suicide had significantly reduced levels of this gene.

Model analysis predicts suicide risk with 80% accuracy

Investigating further, the researchers found that some subjects had an epigenetic alteration that changed the way SKA2 operated - without changing the gene's DNA sequence. This modification added chemicals - called methyl groups - to the gene, they say.

These higher methylation levels were found in the study subjects who had committed suicide, and the team explains that these findings were replicated in two independent brain cohorts.

The researchers next tested three different sets of blood samples, the largest of which involved 325 living participants, and found comparable increases in methylation in SKA2 in those participants who reported suicidal thoughts or attempts.

Based on this, the team designed a model analysis that predicted with 80% certainty which of the participants were experiencing suicidal thoughts or had attempted suicide.

And in those with a more severe risk of suicide, the model analysis was able to predict with 90% accuracy. Based on blood results, the team was able to identify - with 96% accuracy - whether or not a participant had attempted suicide in the youngest data set.

According to the researchers, SKA2 is expressed in the prefrontal cortex, which plays a role in inhibiting negative thoughts and controlling impulsive behaviors. This gene is also responsible for guiding stress hormone receptors into the nuclei of cells so they can function.

However, if there is not enough SKA2 or if it changes in some way, the stress hormone receptor becomes unable to stop the release of cortisol in the brain.

Potential applications

Kaminsky and his team are hopeful that a test based on their findings might be used to predict future suicide attempts in those at highest risk, which could help facilitate interventions.

Potential applications include in the military, where members could be tested for the gene mutation, and if found, could be more closely monitored upon their return home. Additionally, a test would be useful in a psychiatric emergency room, where doctors could assess suicide level risks.

Commenting on their findings, Kaminsky says:

"We have found a gene that we think could be really important for consistently identifying a range of behaviors from suicidal thoughts to attempts to completions. We need to study this in a larger sample, but we believe that we might be able to monitor the blood to identify those at risk of suicide."

He adds that - though it needs further study - the test could potentially be used to inform treatment arrangements, including whether or not to administer certain medications linked with suicidal thoughts.

Recommended related news

Identification and replication of a combined epigenetic and genetic biomarker predicting suicide and suicidal behaviors, Zachary A. Kaminsky, et al., The American Journal of Psychiatry, doi:10.1176/appi.ajp.2014.14010008, published 30 July 2014, Abstract.

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